SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a96dc3924f9f9259acb5910e8c592e715cc958b58117d866ba6935b884651370' 
  AND token = '396sxJ8DwPS2cfMGIZS4sAiO81vcOQhKlaVQiIhCkD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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