SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '50dcec344b11705f12816fd58bcb5a61994657ba2650863bd3747bcfaf2c4a7c' 
  AND token = 'OpVp3g1UFjF0hnfi4lt/DmZk4/COVIEBsX8v9dEex3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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