SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bb971c6313194e0f8e36367a0e70ac8e89299a085962e62419471c9e231fe53' 
  AND token = '1opB2uBYhkZAKBGKySwvz/wrYPkIUcgci8OxmDOIXZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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