SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fe488773ad6e174a282c304ba8f1188ff66229e3d2e7dc30f61d716a39dcf83' 
  AND token = 'RZ59uRlKoXB8iKquXgX2PcHDa4wTFEDYmPSP+bETuMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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