SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '59aa66f46fe1d80cb7bc47e256e283e6d8f6a2a43eedf8051bea5349bb42366c' 
  AND token = 'guleOOmuYFBrpAzV2KQoluyQ5JKjSMRqPjF+S2GK7+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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