SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b15aa2d068e4e5cd733b6c8298fb981546f03e1eb478f0225a39c40d7f6039db' 
  AND token = '+1OTtP5W7wzu+ReVFljGL3D5BzKNGI8q8rsL+jKXgQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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