SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b709c74ff47590b59253ca229ab828da9137424d21fe290aa79fa2f552b59c15' 
  AND token = 'De8AnkDF9d2q8cDdvKzs+iCBJZwhxvXXMMB0xYSE7AU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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