SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'fe98c635f9907dd393edb88fb6754c5c52b721125d67331bec6ca85d3bfad120' 
  AND token = '1cYqwoMWUfh6/00s3FNFJG6mUPBJqBfe0gkJazreEy0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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