SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f674e0019ea751e1c2c3531822bd318c939e96a2dc0b1afb8128cc5114860da' 
  AND token = 'bAv3F1HploMLd13sTnig9P/GOMNC4Bqsa538Ni77Myo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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