SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77ba0ad5394021a656293b9cd0c7dc547f1183824148d479015f897e09f7cd8b' 
  AND token = 'OMhbVmTy4NOzD74DeUu33B9vwsqJqlHRDUmc8L2zYSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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