SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '345703cf67fa0ad328786fe3a174de63c2cb5a3a138d90ae54194978ee7c9cc9' 
  AND token = 'iniWXBcfmysK4ybdo1SIxnztMVaflj6Yoz1wtAVv00k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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