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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6ce6feb3cb3fa0835015ac10535f0fb1acb237c4b0068901377e6bc2a0e5ed2' 
  AND token = 'AKo0JxF/6F87ycxG1n4A3xuXFwUsQ3f5MzNWnpSeB3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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