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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '831c0e1e81f6bc572192ac247958ec420592e0852847429cdabeb581b5e842d2' 
  AND token = 'YXb4g4ZKY8Es/nFf/N2QNT1pHTyl2UrMxT9s9V+/wcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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