SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f51ff628f4fb8cdcec7d6e5daae67b43a16afa843b899da8108465fb6ed1901' 
  AND token = 'lTq6TotT7znCo700nAWchTEpVFoneKZ/CYCucOBJBAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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