SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '02340e37333b0c22470db7582782ae623993aff7bd3b3601d473e145d9920350' 
  AND token = 'yvlTbnUqAiUhE+8cesceI1TzlPwyG2iuWAXZgaR27lU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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