SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4721e96328a8d8e4b8d4d4bed0af5451a0150be0b2692e25ae479132323ff7f4' 
  AND token = 'vQqVDfxs/jPu4A1HC+lYPKUD3Me9dE52RVkxkwo5K60=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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