SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0c68ad1682e3388290a1671778d1b297689f7aa8987f9a808c9ad27957a3e2' 
  AND token = 'YS8EjGNEwQzgsl38xnz2BEJ6qKIhWiCnihyKBcFkrOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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