SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38f44f0387dca426f5124507f221dc67c5ce90a49b59ab68fa49f9cb37abb43d' 
  AND token = 'VxozUilJAJQrtEtrj5Z+Puyi1VBKpITszyJLxvl6h0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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