SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b5548f39ae14b9692431b967da3d825d2f5f5a570e34b401292cf0c10219d97' 
  AND token = 'bMnz7jmRtNmMbUAWUaNqgOmulkGDzwtFKqb+s9uOezs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}