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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d4eddd435b4842dd37fa0ffa876e1a79822bbd0c525b06b9c6a26d3dec55398' 
  AND token = 'mdH/kqUzvCnV1PGA+Rb5aO0kUA5fvlLppVUbG9LQb2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}