SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f6ceb8d1f6b55a1ede7be2d503e741bbd0d963d1c5d209e2d1dd4d6ad839895' 
  AND token = 'PUFvA+zCc0PhbOPn7tY9W3EemBq31b0Z/RpJmlvyAog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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