SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5600dcf27f71a6a17643c6342172853bbb72e5cb8bc817918943f7ee810ddbc3' 
  AND token = 'JltW8Mq/wMUMcRdvwfVzA3FjdLDzfG7TzjsgpSFLCrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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