SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e903f36144a6654e155908ca088e823867376913393ded0114e8d91b818d890' 
  AND token = 'fGV+z4QvzfQvnRdyoJ6+bY5NE/qe4+BPsKIOqYmExLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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