SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2fe4aba1484e7ec5af6b47043e0dafb14223a8cf60d311f2c3f26cbd45b73bc' 
  AND token = 'x1ajC9pAL+o4Vu/vwTnS59YEGQBqUAyhWTe8z/UO0gI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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