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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ccdd895a2418e813ca6c804168e4aa69fb41d1f88b0b75b72d778b472287bb' 
  AND token = 'mQUXBVUlwb4AuJFfbFzYcN3246oHGN3Qmv2RTJrrRhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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