SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '7cb978a8f9bf23e6e9879f2f7d47efcc050a73abf133062db645943f99fc7012' 
  AND token = 'fwtHCItZliKrKLvexpHyoLRPMg8FwLdJihl+c63hkoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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