SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b53c48d75ba60fba1a7866cfd768973903152d263d4f3c3017746fbb278b912' 
  AND token = '9gxstFB/w7UopLQb8v0mq891un+cQgiPPJ8bqcveZoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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