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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '14a5ca697d0bf2b1486ff297f0d1e2897d6efc83a45b5cdb47d1f9da3decd7cd' 
  AND token = 'LfFId2CDtlzTFiIQdexCINiiPLd/pTxGMDNFO7XpLZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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