SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1818d41b597ebb460d1eb9bed7d1365ae30d9ca6e1766d0bf6cb16364a0cdab2' 
  AND token = 'JlxRMG+JsLmadBV1SYgfPP2LYEFPAFh5zgs2/aPhY3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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