SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c21627a8035e97f5c7d3d28471740893e2f6e250399aae779a6491b01245cd9a' 
  AND token = 'HLSwBZcXO8V2ew/frK7t4Cg2aUK5QwpbC2mLUYlUbXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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