SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c39756d418c07ed2b99b2618176fd113c15a3acb7d18b96da302f3a7a97faef6' 
  AND token = 'f9mcwiYZwBXezAAD2kiKFXfSnTJGjfbfEnELQY0uUKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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