SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3899954e1e02fa226bd5bc6bf997eb19b44aed65ff4ca32e72849fd409c3359' 
  AND token = '+QldjXAallgNFopBp5085Hss6dVzGVq1UC6GfzJ1/+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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