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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e803f34bf023d58b31e9a329116c43f2c681623a64378bb6f9fb6a7c7639cfd4' 
  AND token = 'WzqHIP0VjCnZRZd2Iw48e9MtJFal4z6JoxlflE2EZL8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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