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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cd210b66b46c49d0514e61f67833c37e88c677dbc55a3e0fecbca63d094d865a' 
  AND token = 'Cf4fZt3EDa4KtZe+TNojMrCIQkVQieADP5KZ1L3KvqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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