SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cb302d9270557fc555766c666198a4dc6b0d039cc2fb56a8bdd480e8e42c703' 
  AND token = 'BVbaQIObkBbOxxoDU0ToJsYTdyOZ4hkna9q3RRmAcHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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