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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffca51e99e73e50c9632ad62d80db2ccaa0b645fa56e36e5ac14d31d4a54ba3c' 
  AND token = 'JfxQ1s9IfM/3lLgno+QDZ8MwqdkH9k02AprqqDBTNuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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