Sandbox

SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '259cf507715b9525529c419a93583b5d00dbbfab140575c14332f86b92f5b1a2' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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