SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3720aa4c07129e6389224c465f0d4b286fa6eb37735613237c0f61b8e483104c' 
  AND token = 'fREXFMrhJyRsJnCwvHyQnyXZ+3TfAzhstYwEZT0Hj4Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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