SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56b9b276217cea6b1bd298689de4496a5942d8f2e0f5823ddf04819fec12a680' 
  AND token = 'y3iXLvQYYFhu8RRbwnNMpn1LhxmQ3ftoV+ZXnKG7M9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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