SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ab4f48fdaf70cd0e6c17fa32af939563a9739cf9ddea34807cd902f2212018c' 
  AND token = 'AqHNhITzX7Kj9gxrDg2kE6wnqxESHhjlqAWdFMCfYCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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