SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ae1ed9967bed7a53ce579cccd7e424990bc961352b0c1e06ed25269ae4ff29f' 
  AND token = '6FajYjBySZjjo9SsiFozriAW1J8cCOpROEpfpWSbBWA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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