SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a2075b19949f658c2e813196d5a7f7f1d4edffb9512014a9679a2b8939ec871' 
  AND token = 'r41jrvDlG/NX6Fv9bt/CVhOcZjQAUJYaeF+o/FgjSa0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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