SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '31387f5f476f5b5da8d24bed042feb95ecee608f621c80780b0738d89af03561' 
  AND token = 'l7Tnv37fV0GRRkg5gTaBYNdV8Hth5drYP4SAvUw+/kM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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