SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78eb594da105312195d6bb223bc5beaf8285c6024236b9075303d73830f2ae4d' 
  AND token = '7dZRz2m5a9HeiZVWfrEO5d13/VZVnbiVIWj7dNTaflQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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