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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a0a2be4f4d15cf6db640c528140275b2a3c1e15a79b8807f41ff837c832a434' 
  AND token = 'WT3tUdpv7d+mdpPVUYN3zcYX1uW78ANIUSCsPJC7ZwQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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