SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd08b1871b7d61242eb392256fd64973be313678a09367b182a7516daba0d10c' 
  AND token = '0l4ljtJMXdXp7Ao82Z3NwE+MvVB1SAs7FmZZkZ2lLAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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