SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e10a7c0793262555a45cb76ed7cc651ccccf3114ca3b2d44824998337f90d89' 
  AND token = 'UsNhGTJIoROE3blHLhYaSkmbAddMbwMY83pR0sqPqkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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