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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bf7bc25755e8c046624ad91bb8403b5c51ebbf09f75eaaf50f8d1bebe5e5d3b9' 
  AND token = 'erHu1xRiRytCM+tlyeSt/H58dTJxsJaZzMw1S0liw9I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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