SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '2ccd9a6b333ce6cb5f5c4edc41e3d1dd1e3329ad73ce61a0036c09495741de5a' 
  AND token = 'mx/tDdzqZEl7+YOj3lDxOpWt8I+cnbxkKjG+HALOxkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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