SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c7751d56b84973fc806322225bda8f877f6e2bf938978f60bce779a923009c8' 
  AND token = 'HVhc8fkvcl+6qlIS+zTBHsJmnpy05egOruyyicPsRhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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