SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b552e00e9859752f4d67bf481799f8056e13169074df2f0361535cd313a17dd7' 
  AND token = 'PuAwM7vq04gcICh59b0Jr5N8rl+yePK8iAvFw8vcuGQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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