SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d2c40d95801d88487c50f0e83749547c483e07029bda703d3550f6c4f170639' 
  AND token = 'YTHh/oAh9oDNOctASpfVPei+Irnf+IBiOAxlfI08ub4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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