SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a12134c1e15182b94ef48e6060be383b1142a0ca2507fe636a69f7db503dc4' 
  AND token = 'H1I1wXFyRBOV//tLBcHXDO1gnp4DFcnD0gLvQbpDrTI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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