SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af84e449446dc7f2cfb1fce1bfa7773b4c04ca44f565ada35ddbeebe55dea3c3' 
  AND token = 'EkaH0BMryJrY8nrbdnjrlS6EPF50HDlDtTMcGy7xx+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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