SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f84f18dcbd38c2133c065f3b2b16533f081a3cac4a767344f6814c7fef83e981' 
  AND token = '2hmILob7FLbLiwhTZwmIbwEvybHgFr10E23ltc5/jBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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