SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '990a39f757e346dc345b64c754c6b990f3a179c5237e42ed71018967316f28b3' 
  AND token = 'IphA1fkwi0CtqyySURP3UmtcnVl3dx03h7qddbXLgLk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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