SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'af520af82c340fceeea7a99a040a696746049c4dbff7fb50490a23af5b423e1c' 
  AND token = 'G0Iy3Oz4hHHg25167Ysp894+9pdCfMBNdTlla7DufsM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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